Phonographic sound reproducer



Aug. 10 1926.

A. A. THOMAS PHONOGRAPHIC SOUND REPRODUCER 2 Sheets-Sheet 1 Filed Jan. 29, 1926 INVENTOR A. A. THOMAS PHONOGRAPHI C SOUND REPRODUCER Aug. 10 1926.

Filed Jan. 29, 1926 2 Sheets-Sheet 2 DIAPHRAGM W R T C E L E INVENTOR Patented Aug. 10, 1926 I UNITED STATES ADOLPH A. THOMAS,

OF- NETH YORK, N. Y.

PHONOGRAPHIC SOUND REPRODUCER.

Application filed January 29, 1926. Serial No. 84,551.

This invention relates tothe art of reproducing recorded sound, and its object is to provide a new and improved reproducer for phonographs or similar acoustic machines utilizing sound recordsfor loud reproduction. I

Briefly stated, the fundamental idea of my invention comprises a combined electromechanical 'reproducer' asa single unit capable of reproducing from a record either mechanically through a diaphragm, or electrically through suitable electromagnetic mechanism. The device is readily adjusted for either method of reproduction. The advantages of this double-acting rep-roducer will presently become clear.

The acoustic reproduct'on of phonograph records has heretofore been carried out in two ways: first, mechanically by means of a diaphragm actuated by therecord needle, the diaphragm vibrations being amplified through the tone arm and horn of the machine; second,. electrically by causing the needle to o eratea microphone or an electromagnetic evice mounted on the tone arm for producing variable currents in a tele-.

'phone receiver, which may be located in the phonograph cabinet or at a distance therefrom. In this electric reproduction, the tone arm is not utilized as an amplifier of sound waves, but the telephone receiver is acoustically connected with an amplifying horn or operates through a loudspeaking diaphragm. In phonographs utilizing mechanical reproduction, the maximum volume obtainable is necessarily-limited bythe maximum vibrations of the needleiaetuateddiaphragm as amplified through the tone arm and the horn. The volume of sound thus produced is usually sufficient for an ordinary room in a house or an apartment. But there are times when it is desirable to obtain a greater volume of reproduction from a record than is possible with a mechanical sound box-as, for instance, where is played in a largeihall ora phonograph in the open. To meet this condition, it has been proposed to use an electric reproducer in which the needle operates a microphone or otherwise causes variable currents to fiow in a telephone receiver. jThese currents may be amplified or stepped up to increasethe' volume of reproduction to the It is recognized that" each method of :p on gr p ie soun p r de? tio nthat is, the mechanical and the electr1cal--has its advantages: the mechanical method requires no batteries, circuits, etc.,

and the electrical method permits greater has a single needle arm, a diaphragm mechanically actuatedby the needle arm, and electromagnetic mechanism including a vibratory member connected to the inner end of the needle arm. The electric reproduction takes place independently of'thediaphragm and so the operative connection between the needle arm and the diaphragm isseparable. I provide means for selecting either the diaphragm or the electric mechanism for reproducing operation, and this selecting means is preferably controlled by a suitable finger piece outside the reproducer casing. The selecting means may also control the circuit connections of the electric reproducing'mechani'sm.

The basic 1dea of my invention may be I embodled in various constructions, of WhlClltwo exam les are illustrated in the accompan'ying rawings, where.

Fig. 1 shows an interior face view of an electro-mechanical reproducer embedying my invention;

. Fig. '2 is a cross-section onthe broken line 2-2 of Fig.1, the diaphragm being shown connected to the needle' arm;

Fig. 3 represents a transverse cross-section on the broken line 33 of Fig. 1;

Fig. 4 is a view (partly broken away) similar to Fig. 2, but showing how the connection between the diaphragm and needle arm is broken;

Fig. 5 is a fragmentary detail view to illustrate how the adjustable selecting member, by means of which either thediaphragm or the electric reproducing mechanism ,is rendered operative, automatically closes the circuit of the electric mechanism when the diaphragm is disconnected;

Fig. 6 is a fragmentary face view of the lower portion of the reproducer casing to show the two positions of the selecting arm;

Fig. T illustrates an interior face view of tion material.

I pole pieces are preferably vibratory movement.

a modified construction, certain parts being shown in section on line 77 of Fig. 8;

Fig. 8 is a cross-section on the broken line 88 of Fig. 7, showing the needle arm connected to the diaphragm;

Fig. 9 is a transverse cross-section on line i 99 of Fig. 7;

' Fig. 10 shows a view (partly broken away) similar to Fig. 10, with the connection between the diaphragm and the needle arm broken; and

Fig. 11 is a fragmentary face view of the outer casing to indicate how the selectlng knob should be turned for obtaining electric or mechanical reproduction.

In order to make the drawings as clear as possible, I have purposely exaggerated the dimensions and relative proportions of the different parts, which have been spread out considerably more than would be necessary in actual practice. These drawings are therefore not to be taken as shop drawings.

I shall first describe the construction shown on the first sheet, Figs. 1-6. A suitable casing G houses the various parts that comprise the interior working mechanism of the instrument. The casing G is here shown as consisting of a back plate 1, a cylindrical body section 2, and a front plate or cover 3. These three parts may be sep arably connected, as by screws 4 engaging in peripheral bosses 5 of section 2. The casing may be constructed of non-magnetic metal, such as brass, aluminum, or aluminum alloy, or it may be shaped out of suitable composi- The body section 2 is provided with a transverse annular flange 6 arranged to form a shallow recess or chamber 7, in which is mounted an acoustic diaphragm 8. This diaphragm is held rigidly clamped at its periphery in any practical way. For simplicity, I have shown diagrammatically a pair of non-metallic rings 9 between which the diaphragm is held for The diaphragm is easily inserted in position through the open mouth of recess 7 before the back plate 1 is screwed on. v 5

A magnet M, preferably of the permanent type, is supported within the casing. In the present instance, the magnet is secured to the annular flange 6 by screws 10 or otherwise. The flange 6 thus performs the double function of supporting the magnet and serving as part of the mounting for the diaphragm. By making the magnet of circular shape, as shown in Fig. 1, it is possible to obtain a maximum length of .magnetic path in a small cylindrical casing. The ends of magnet M are turned forwardly at 1 1 for receiving pole pieces 12 o f'soft iron. These cylindrical and are arranged in axial alignment to provide anairga 13. I

A nee le arm 14 is pivotally mounted on netic lines of force to This will be understood bythe electrical art without the need of further explanation. By connect-. ing the coil in suitable circuits these currentcasing C by anypractical means. For convenience, I'have shown the casing provided with a pair of lugs 15, between which is supported a spring blade 16 of proper strength and resiliency. This spring passes through (or is otherwise rigidly connected to) the needle arm near the outer end thereof, which constitutes a needle holder 17. The tension of spring 16 permits the needle arm to vibrate transversely of the casing, as about a pivot, and the strength of the spring is amply sulficient to take up the longitudinal thrust on the needle arm in the playing of a record. The spring blade 16 thus serves as a pivot support for the needle arm and as a restoring or centering spring for the same. Any other suitable support for the needle arm may be employed. A slot 18 in section 2 of the casing permits the insertion of the needle arm into the casing and allows free vibration of the arm.

To the inner end of needle arm 14 is rigidly connected a coil 19, as by means of a strap or-band 20 clamped tight around the coil. screw or rivet 21 to the needle arm. The coil is arranged to vibrate in the airgap 13 of the magnet. In the normal position of the needle arm, the coil 19 is substantially in axial alignment with pole pieces 12. The internal diameter of the coil should preferably be about the same as of the pole pieces. As the needle arm 14 vibrates, the coil 19 vibrates transversely of the pole pieces and thereby cuts the maggenerate electric current impulses. those skilled in impulses can be utilized to operate a loudspeaker or any other reproducing device. It is clear from Figs. 1 and 2 that the needle vibrations are transmitted to the coil in amplified ratio, so that the smallest vibrations of the needle point are suflicient to generate current impulses in the circuit of the coil.

It is to be noted that there is no magnetic drag or load on the needle arm during Vibration of coil 19.

In the broad aspect of my invention, the magnet M and coil 19 represent merely one of many practical forms of electric repro-- 'duclng mechanism operated or controlled by the vibrationsof the needle arm. I do not, therefore, intend to be limited to any particularconstruction of electric reproducing The ends of strap- 20 are secured by a the diameter v means, provided it is capable of operation independently of the diaphragm. One of the important features of my invention lies in the fact that the electric reproduction takes place without the diaphragm, which is used solely for, mechanical reproduction through the tone arm on which the reproducer is mounted. To accomplish this rea controlling member 29 pivoted .-on a pin sult,=-I provide'ga readilyi separable and reand ithe needle :arm'.

A novel "idea n'ay be mechanically carried out.

. wayofexample in Figs-.1 6.

'tion 33 *formed sto'ra'ble connection between; the ..-'diaphragm in various ways, one of which is shown by i The diaphragm '8 is' provided at the center with a U-shaped. lug-22.carrying a cross-pin-23, to which i's-pivoted a lever 24.

"At a suitable point-between its ends the lever 24 is formed with a slot 25 adapted:

to hook tightly over a pin 26 projecting laterally from the needle arm 14. The member-24. may-= be referred to as a hook or coupling. The parts shouldbe so proportioned and designed that, when the'slot 25 engages the pm 26, the diaphragm and needle=arm are securely coupled together to vibrate as =a unit. The free end 27 of coupling=24 extends into a cam slot 28. of

nates in a finger piece 36. The outer end "of arm 34 is preferably curved forwardly, so

v that the finger piece projects beyond the casing for easy manipulation.

The-curvature of cam slot 28 in the handoperated member 29 is such that, when this member is moved into the position shown in Fig. 1, the-cou'pling-24 is forced down until theslot 25 hooks firmly over the pin-26 of the needle-iarm, as best shown in Fig. 2-. The 'movei'nentof finger piece 36 toward the left ordiaphragm -position (see-Figs. 1

: and-'6) is automatically'arrested when' the arm, ti l-strikes the end o'fslot 35. A spring 36 -in Fig. -6, the. cam 'slot. 28 raises the.

, condition,

1 as- "the electr finger --37- may:

right or"-el'ectric-- position, as indicated at coupling-hook.-24=-out 'of engagement with pin=26, thereb needle arm fromdiaphragm 8. Under this mechanism. without actuatlng the dia-p The "disconnection of-- the-dia phr'agm 'from'the -'needle arm during electrie' reproduction is one, of-thebasic fea- I .ment is operated .for mechanical reproduc'- tion throughthediaphragm. In the present pliragnlI-l tunes"of'my-invention'. It makes-it possible. 'touse the sam horn inia phonograph cab-' inet-for-"amph This fundamentally course, if the current COll 19, or whatever electromagnetic dGVICG may beoperated by the needle,arm,:are con-' 7 :into the enlargement. 28'.

-with the diaphragm, matically disconnectedfrom the connecting be used -to engage the 'a-rm' 34" frictionally andthereby retain the controlling member=29* in' actuated-position against' possible rattling or accidentaldisplacement. When the finger piece 36 is moved to the entirely disconnecting the "Fim i'. *thea n'eedle' arm may be used; to operate or" control the electric reproducing 1 fying the mechanical as well cal reproduction: The Alias ph'ragm'; tit.f. oeswithout saying, samplifies through the tonje=arm-which connects .with-".-i-U'-shaped -.fra-me-';-3L;,

the hortfi "The current impulses geii'erated -jpontedmetheeas1ng. To-thecont-actsi38 and;

by the electricreproducing iiine ans' operate or control. a loudspeaking telephonereceiver' whicht'may be acousticall connected with the same-horn as the diaphragmflon the tone arm, This requires-that the diaphragm must not vibrate during the operation of the -"electric: reproducing mechanism. Of impulses generated by veyed to a. loudspeaker situated atya dis-- .tan'ce beyond the-hearing of a person near the phonograph cabinet, it. is possible to have'mechanical and electrical reproduction at the same time, provided the circuit through coil 19 remains closed during the operation of the diaphragm. Whilethe in-' strument of my invention is capable of such. use, the primary object is 'to provide a combined mechanical and electrical reproducerinv which the electrical reproduction can take place without operating ,thediaphragm.

I shall .now direct attention tothe en largement 28 provided at one-end of cam slot 28. the end 27 of coupling 24 enga es the-walls of theslot in a snug fit during t emovement of cam member 29 in either direction. For

this purpose, the walls off slot 28 are preterably formed .on a slant,'a's indicated in 1 andb, to-accommodate'the pivotal movements of the coupling-arm 24 without lost motion. Now, when the controlling member 29 has almost reached the end of its movementto-connect theldiaphragm with 1151 the. needle arm, the projecting end 27 of the i The widthof thisslot is such that" coupling-arm'passes out ,of the cam slot 28 In other words,- after. the member-29. has been operated by finger piece 36 toconnect the needle. arm' the member 29 is autoneedle arm without-interference by the controlling member 29-. The other end of cam lar-to 28, because the member 29 may remain connectedwith' the coupling 24 when the-needle arm is-disconnected from the 3 diaphragnn This willbe' understood v:tromo that :no unnecessary waste of battery current may occur during intervals in which the electricreproducing mechanism .is not used, I provide means forautomatically o ening. suitable switch connections .in the e ectricreproducer'circuit when the instruembodiment I- have shown a pair of switch contacts 33- and '39 mounted: 'on an; insulating bracket gar-m :40, which s .secured to. the-:1 oris, .otherwise -supl'lU slot 28.1does not require anenlargement siminected to contacts 38 and 39.

'- 39-are connected the end conductors 41 of lecting member29 ,carriesan insulated cam. pro1ection 43 arranged to engage the con-.

tact 38 and force'it'against the contact 39 when the member 29 disconnects the needle arm from the diaphragm. This position of member 29 is shown in Fig. 5. It is understood, of course, that the finger piece 36 is not moved into the electric position 36 (see Fig. 6) unless and until the instrument phragm', so that the needle. arm is operis to be used for electric reproduction. In

the broader aspect of my invention, the contacts 38 and 39 represent aswitch in any part of the electric reproducing circuit or system of which the coil 19 is an'element.

The switch 38- 39 may be omitted to. permit simultaneous electrical. and mechanical reproduction.

-- l hereproducer z-casing is op'erativcly mounted on a tone arm 41, as by means of a hub 45 -projecting from the back plate 1 ofthe casing. A set-screw 46, engagingin-a slot ot-hub 45,. determines the correct position-of the reproducer on the tone arm. The leads 42 are connected to binding posts '48 mounted on an insulated disk 49 attached to ;the backplate of the casing, asfillustrated in Fig. 2. Only one of the binding posts 48 is showmbut the construction-iis clear enough. Conductors 50 are separfably connected to the binding posts 4,8-"anda' lead' through" an'opening 51 in hub into ithe tone'armfis 'as to be concealed from wiew; The conductorsare properly connected in. circuit, as'iwill be understood withoutffurther description. To'remove the repro'du'cer casing, it' is. only necessary to disconnect the conductors 50 from binding posts-48 and loosen the set-screw 46."

Theiimodification of Figs. 7-11 differsfrom-theconstruction of the preceding figures inthe' mechanism for selectively connecting. and disconnecting the diaphragm and needle arm.- To avoid useless repetition in explaining Figsn7-1l, I shall omit a detailed description of all those. parts that were previously described in reference to Figs. 1-5. 'It will be sufficient to' mark corresponding parts in the two sets of views with like reference characters. The diaphragm 8 in Figs. 7-.l0 is provided at the center witha screw-plug52. The needle arm l4'has rigidly secured .to its. screw-threaded socket 53 in which is supported'a screw 54 rovided at its outer end with" a pinion 55.

he screw 54 is adapted to engage inthe screw -threaded plug 52. On the frontplate or cover of the casing is formed 'a bearing 56 in which is journalled an arbor or stub-- shaft 57. A suitable linger piece 58, here shown as a knob, is fixed to the outer end 'of shaft 57, andto the inner end of this shaft is connected 9. gear 59 arranged to mesh with pinion 55. The gear 59 does not have a complete circle of teeth, but has a cut-away or mutilated section 60 whlch does not engage the pinion 55, for aurpose that will presently be explained. fixed stop 61. on the casing engages a stop 62 on gear to limit the movement of the latter in either direction. p

The operation -of the selective connecting mechanism of Figs. 7-10 is as follows: Let us assume that the screw 54 is in engagement with the plug 52 of the diateeth of gear 59 engage the pinion 55 and rapidlv rotate the screw 54 in a clockwise or right-handed direction. The screw 54 being left-handed, this turning of the screw moves the same out of plug 52 to-disconnect the needle arm from the diaphragm. Vhen the lug 62 on gear 59 strikes one side of.

the fixed stop 61, the screw 54 is in the position shown in Fig. 10 and further movement of the knob 58 in the direction a is prevented. By providing an opening 55' in the cover of the casing in alignment with pinion 55, the width of the casing may be reduced without danger of the pinion striking the casing-when the needle arm vibrates. The-pinion 55 is long enough to permit continued engagement with the gear-59 during the axial movement of screw 54 from its connecting position in 9 to its withdrawn position in Fig. 10. To connect the needle arm again with the diaphragm, the

knob 58 is turned in the direction of arrow b in Fig. 11, whereby the pinion and screw .are rotated counterclockwise until the lug .62 of gear '59 strikes the other side of stop 61. The screw 54 is then in the connecting position'shown in Fig. .9,- and the gear 59 is fully disconnected from /the pin1on. It may be ."found desirable to insert a pad '63 of hard rubber-or otheryieldable material in the bottom-of plug 52 to produce a final jamminglefli'ectas the screw 54 reaches home and resses against the-pad. Hlhisproduoes a ti t solid joint betweendiaphragm and needle arm, and yetit-is -ajointthat ls-e'asily separated:-byai;mere turn-cf knob 58.. To-

and number-of screw-threads in screw 54,-

thatone .turn of gear.59 moves the screw into and out of connecting position. ;I have not attempted to indicate these transmission ratios withmathematical precision in the j -when'the latter is selected for reproducing drawings.

lhe operator can readily tell, by simply feeling the knob 58, whether the diaphragm and needle arm are connected or disconnected. For instance, looking at Fig. 11, if the operator tried to turn the knob clockwise and-found it locked against movement in that direction, he would know at once that the needle arm was connected to the diaphragm and that, therefore, the instrument was in condition for mechanical reproduction. Conversely, if the operator found that he could not turn the knob in the direction of arrow a in'Fig. 11, he would know that the instrument'was set for electric reproduction. Y

The automatic switch control described in connection with Figs. 1 5 may obviously be embodied in .Figs. .6l0, but I have not considered it necessary to encumber the drawings with a superfluous duplication of this feature.

It will be seen from the foregoing description that I have devised a combined mechan ical and electrical sound; reproducer in asingle unit capable of ready adjustment for either method ofreproduction. The same horn in the cabinet containing the reproducer may be used for amplifying both. the

mechanical and the electrical reproduction. This is made ossible because the'electric reproduction ta es place independently of the...

diaphragm and without vibration thereoi.

As far as I am aware, this characteristic. 7

' casing, a diaphragm insaid casing, a needle arm, an ad ustabIe "connectm element be-f feature of my invention isfu'ndam'entally Although I have shown and described cer tain constructions,- I have done so for the sake of explaining indetail lt'w'o .embodiments which at the present time: serve best to express my ideas, and not byway of re-' striction orlimitation. It is manifest that" i the various features of my inventionmay be I carried out in other vways than herein, set

forth without departing from the scope of the invention as defined in the following claims. a What I claim as my invention-is:

-1. A sound reproducer comprising-v a mechanically actuated arm', a-nd mechanical and electrical 'sound reproducing means .3. A phonograph reproducer unit having. a diaphragm .and electric reproducing mechanism, means for selecting either said diaphragm or said mechanism for reproducing operation, and a switch automatically ope r ated by the movement of said select-ingmeans to close an-electric circuit of said mechanism operation, said-switch being automatically opened when the'diaphr'agm is selected for operation." I

4. ,Ina phonograph reproducer, a dia-- phragm, a needle arm, an ad ustable member for connecting and disconnecting said diaphragm and arm, and. means for operating said member, said operating means being automatically disconnected from said mem- 0 I her when the latter has been moved into connecting position.

5. A phonograph reproducer unit having a needle arm, a diaphragm actuated by said arm, electriczreproducing mechanism, and means for operating said mechanism without actuating said diaphragnt p 6. A phonograph vreproducer having a needle arm, a diaphragm actuated by said arm, electric reproducing. mechanism also operated by said arm, andmanually adjustable, means for, rendering the connection between said armand said-diaphragm inoperative during the operation of said electric mechanism.

7 In a honograph reproducer having a cas'ing, a diaphragmin said casing, a needlearm independently of am, an adjustable connecting'element be tween said diaphragm and said arm for'con; nectmg and"disconnecting-those twoparts,

' casing. for adjust ng said elementinto con and a member operable from outside. said eating. and dlscpnnecting-positions.

1.8.- In a phonograph reproducerhavinga tween said-diaphragm and-said a'rm for con- J nectmg and disconnecting thoseftwo p'arts;.

and a member operable from outside said casing; for adjusting said element intoconnecting and disconnecting position, said member being-J separable" from said element: when the' diaphragm; and needle arm are:

connected.

tio'n through the tone arm-during the-elect-rical reproduction.

iso

10. In 'soundreproducing mechanism, a

diaphragm and a telepl'rone transmitter, a

i'neans toprevent' operation of said diaphragm during the operation of said transmitter by said member.

11. A phonograph reproducer comprising a casing, a needle arm pivot d to said casing, a diaphragm mounted in s id casing, an adj ustable coupling between .aid arm and said diaphragm, a movable finger piece projecting' outside said casing, a member operable by said finger piece to move said coupling into and out of operative position, means; whereby said member does not interfere with the operations of the diaphragm, and electric reproducing mechanism in said casing, said mechanismincluding awvi'bratory member connected to saidarm,

12. A phonograph reproducer comprising a casing, a needle arm pivoted to said casing, a diaphragm'mouuted in said casing, an adjustable coupling between said arm and said diaphragm, a movable finger piece projectin outside said casing, member operable y saidfinger piece to 'move said coupling into and out'of operative position, means whereby said member is auta'nnatically disconnected from said coupling ,when the latter is operated to connect the "(liar phragm to, the needle arm, and electric reproducing mechanism in said casing operated by said arm.

13. A phonograph reproducer comprising a casing, a-needle arm pivoted to said casing, a diaphragm mounted in said casing, a

. pivoted hook for "operatively connecting said arm and said diap ragm, a pivoted member having a cam slot, an extensionon said hook arranged to engage in said slot, wherebv operation of said cam member moves' sai hook into connecting and releasing positions, said cam slot terminating at one end in an enlargement for freely receiving said extension when the hook connects the diaphragm with the arm, so that said cam memher is disconnected from said hook when the needle arm actuates the diaphragm, a slid able finger piece projecting from said casing for operating said cam member, and a telephone transmitter mounted in said casing and having a vibratory member connected to said arm.

14. In a combined mechanical and electrical sound reprodu'cer, a diaphragm, an acoustically actuated arm for o eratmg said diaphragm, a readily separableand restor- -able connection between said parts and 'i'or connecting and disconnecting those two parts, and a rotary member operable-from outside said casing for adjusting said-ole meut into connecting, and disconnecting positions. a

l6. In-a phonograph reproducer having- 1 casing, a diaphragm in said casing, 13/

.ieedle arm, an adjl'istable connecting ele nent between said diaphragm and said armfor connecting and disconnecting those two parts, a member operable from outside said :asing for adjusting said element into con- ,iecting and disconnecting posit-ions, and means whereby said member is automatically disconnected from said element when the latter has been moved into connecting .pcsition.

17. A phonograph reproducer unit having a dial'ahragm and electric reproducing mechanism, and means for selecting either said diaphragm or said mechanism for reproducing operation.

it A phonographreproducer comprising a casing containing a diaphragm and electric reproducing mechanism, and an adjustable finger piece outside said casing for placing either said diaphragm or said mechanism in condition for reproduction.

1.9. A pl'ionograph reproducer having a needle arm, a diaphragm actuated by said arm, electric reproducing mechanism including a coil, means for operating said mechanism through said arm independently of said diaphragm, and means whereby the circuit of said coil is automatically broken when the diaphragm is operatively con nected to said arm.

20. In a sound .reproducer, a mechanically actuated dia hragm, electric reproducing mechanism a apted to be operated independently of said diaphragm, said mechanism including a coil, a switch for controlling the circuit of said coil, an adjustable connecting device for selecting either said diaphragm or said mechanism for reproducing operation, and. means controlled. by said device for automatically opening said switch when the diaphragm is'connected for operation, said switch beingautomatically closed when said device is adjusted to obtain re-j production through said mechanism.

a A oLPH A; THOMAS. 

